Infiniti QX56 (Z62). Manual — part 514
EC-34
< SYSTEM DESCRIPTION >
[VK56VD]
STRUCTURE AND OPERATION
On Board Refueling Vapor Recovery (ORVR)
INFOID:0000000006217696
From the beginning of refueling, the air and vapor inside the fuel tank go through refueling EVAP vapor cut
valve and EVAP/ORVR line to the EVAP canister. The vapor is absorbed by the EVAP canister and the air is
released to the atmosphere.
When the refueling has reached the full level of the fuel tank, the refueling EVAP vapor cut valve is closed and
refueling is stopped because of auto shut-off. The vapor which was absorbed by the EVAP canister is purged
during driving.
WARNING:
When conducting inspections below, be sure to observe the following:
• Put a “CAUTION: FLAMMABLE” sign in workshop.
• Never smoke while servicing fuel system. Keep open flames and sparks away from work area.
• Always furnish the workshop with a CO
2
fire extinguisher.
CAUTION:
• Before removing fuel line parts, carry out the following procedures:
- Put drained fuel in an explosion-proof container and put lid on securely.
- Release fuel pressure from fuel line. Refer to
.
- Disconnect battery ground cable.
• Always replace O-ring when the fuel gauge retainer is removed.
• Never kink or twist hose and tube when they are installed.
• Never tighten hose and clamps excessively to avoid damaging hoses.
• After installation, run engine and check for fuel leaks at connections.
• Never attempt to top off the fuel tank after the fuel pump nozzle shuts off automatically.
Continued refueling may cause fuel overflow, resulting in fuel spray and possibly a fire.
PBIB1068E
SYSTEM
EC-35
< SYSTEM DESCRIPTION >
[VK56VD]
C
D
E
F
G
H
I
J
K
L
M
A
EC
N
P
O
SYSTEM
ENGINE CONTROL SYSTEM
ENGINE CONTROL SYSTEM : System Diagram
INFOID:0000000006217697
ENGINE CONTROL SYSTEM : System Description
INFOID:0000000006217698
ECM controls the engine by various functions.
JSBIA0590GB
EC-36
< SYSTEM DESCRIPTION >
[VK56VD]
SYSTEM
DIRECT INJECTION GASOLINE SYSTEM
DIRECT INJECTION GASOLINE SYSTEM : System Diagram
INFOID:0000000006217699
DIRECT INJECTION GASOLINE SYSTEM : System Description
INFOID:0000000006217700
INPUT/OUTPUT SIGNAL CHART
Function
Reference
Fuel injection control
EC-36, "DIRECT INJECTION GASOLINE SYSTEM : System De-
scription"
Fuel pressure control
EC-39, "FUEL PRESSURE CONTROL : System Description"
Cooling fan control
EC-41, "COOLING FAN CONTROL : System Description"
Electric ignition control
EC-42, "ELECTRIC IGNITION SYSTEM : System Description"
Intake valve timing control
EC-43, "INTAKE VALVE TIMING CONTROL : System Description"
VVEL (Variable Valve Event & Lift)
EC-44, "VVEL SYSTEM : System Description"
Evaporative emission
EC-45, "EVAPORATIVE EMISSION SYSTEM : System Descrip-
tion"
Air conditioning cut control
EC-47, "AIR CONDITIONING CUT CONTROL : System Descrip-
tion"
ASCD (Auto speed control device)
EC-48, "AUTOMATIC SPEED CONTROL DEVICE (ASCD) : Sys-
tem Description"
Power generation voltage variable control
CHG-7, "POWER GENERATION VOLTAGE VARIABLE CON-
TROL SYSTEM : System Description"
JSBIA0471GB
SYSTEM
EC-37
< SYSTEM DESCRIPTION >
[VK56VD]
C
D
E
F
G
H
I
J
K
L
M
A
EC
N
P
O
*1: This sensor is not used to control the engine system under normal conditions.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
The adoption of the direct fuel injection method enables more accurate adjustment of fuel injection quantity by
injecting atomized high-pressure fuel directly into the cylinder. This method allows high-powered engine, low
fuel consumption, and emissions-reduction.
The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of
time the valve remains open (injection pulse duration). The amount of fuel injected is a program value in the
ECM memory. The program value is preset by engine operating conditions. These conditions are determined
by input signals (for engine speed and intake air and fuel rail pressure) from the crankshaft position sensor,
camshaft position sensor, mass air flow sensor and the fuel rail pressure sensor.
VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION
In addition, the amount of fuel injected is compensated to improve engine performance under various operat-
ing conditions as listed below.
<Fuel increase>
• During warm-up
• When starting the engine
• During acceleration
• Hot-engine operation
• When selector lever position is changed from N to D
• High-load, high-speed operation
<Fuel decrease>
• During deceleration
• During high engine speed operation
FUEL INJECTION CONTROL
Stratified-charge Combustion
Stratified-charge combustion is a combustion method which enables extremely lean combustion by injecting
fuel in the latter half of a compression process, collecting combustible air-fuel around the spark plug, and form-
ing fuel-free airspace around the mixture.
Right after a start with the engine cold, the catalyst warm-up is accelerated by stratified-charge combustion.
Homogeneous Combustion
Sensor
Input signal to ECM
ECM function
Actuator
Crankshaft position sensor
Engine speed*
2
Fuel injection
& mixture ratio
control
Fuel injector
Camshaft position sensor
Camshaft position
Mass air flow sensor
Amount of intake air
Intake air temperature sensor
Intake air temperature
Engine coolant temperature sensor
Engine coolant temperature
Air fuel ratio (A/F) sensor 1
Density of oxygen in exhaust gas
Fuel rail pressure sensor
Fuel rail pressure
Throttle position sensor
Throttle position
Accelerator pedal position sensor
Accelerator pedal position
TCM
Gear position
Battery
Battery voltage*
2
Knock sensor
Engine knocking condition
Power steering pressure sensor
Power steering operation
Heated oxygen sensor 2*
1
Density of oxygen in exhaust gas
ABS actuator and electric unit (control unit)
VDC/TCS operation command
A/C auto amp.
A/C ON signal
Combination meter
Vehicle speed
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